Fast Diskrom

On ebay sometimes I see MSX2 computers with a 'Fast DiskRom' I wonder, is this an adjusted MSX2 DiskRom or is this the MSX2+ DiskRom ?
I have the possibility to program my own eprom's and als have the 2+ rom files, so if the fast diskrom is the 2+ rom I can try this out on my NMS8255, if it is not the 2+ rom, but an adjusted MSX2 Diskrom then I would like to know were I can find the Rom files to do this adjustment.

SLotman: hehe, I don't think he means Fast! Diskrom. Since a long time there have been adjusted EPROMs in the Netherlands with a faster diskROM than usual. In my own Sony HB-G900P, for instance, there's a modified NMS 8245 diskROM, which is much faster than the standard Sony diskROM.

If someone's interested, I guess I could dump it, so that you can study it.